Oral fluids are inexpensive to collect. Each pen sample requires a length of cotton rope, a plastic bag, and a snap-cap plastic tube. Labor costs include the time required to place and recover the ropes, plus time to process the sample. Additional expenses include shipping and laboratory (PCR) costs. We found that the use of oral fluids worked very well in conjunction with PCR-based diagnostics for PRRSV and PCV2. We believe that it will be possible to develop antibody-based assays that use oral fluids in the future. In addition, research currently under way will eventually result in rapid on-farm diagnostics that use oral fluids. Based on our experience, we are currently recommending sampling at 3-4 week intervals for surveillance of PRRSV and/or PCV2. The number of samples to collect per site or building depends on the specific objective, the site, and facility design. Precise estimates of the number of samples necessary for effective surveillance of buildings, sites, or populations will require additional research. In our experience, circulation of PRRSV and PCV2 in grow-finishers barns was detected using 6 samples per building (~15% of pens).